Study on the Mechanism of Temperature Effect on SO₂ Electrochemical Gas Sensor

Temperature can affect the measurement values of electrochemical gas sensors, increasing measurement errors. The influence mechanism of temperature on electrochemical gas sensors was studied based on Fick’s first law and the limit diffusion current formula. Temperature affects the sensitive characteristics of a sensor by changing the diffusion coefficient D l 1 of SO 2 in air, the Henry’s coefficient K H of SO 2 dissolved in water and the water content of the electrolyte solution. When the temperature increases, the degree of influence of Henry’s coefficient K H and the reduction of the water content is greater than the degree of influence on the increase in diffusion coefficient, which decreases the sensor measurement value. The results of the temperature experiments show that the optimal temperature range for the sensor is −25 °C to 50 °C, and the average measurement error in this temperature range is less than 20%. When the temperature exceeds 50 °C, it will cause a reduction in the evaporation of water in the electrolyte solution, leading to a rapid increase in the measurement error. The structure of the sensor can be improved by adding a water retention layer inside the sensor to supplement the electrolyte solution with water, so as to reduce the measurement error.